Procedurally, the Medicines Company (“Medicines”) owned two patents. In response to an Abbreviated New Drug Application (“ANDA”) submitted by Mylan, Inc. (“Mylan”), Medicines filed suit in the United States District Court for the Northern District of Illinois alleging that Mylan’s ANDA infringed claims of two of its patents. Mylan counterclaimed seeking a declaration that the asserted claims were invalid.

The district court then held on summary judgment that the asserted claims of one of the patents were not infringed because Mylan did not satisfy the “efficient mixing” limitation of those claims. After conducting a bench trial, the district court held that the asserted claims of Medicines’ other patent were infringed because those claims did not include the “efficient mixing” limitation. The case was then appealed to the Federal Circuit.

According to the Federal Circuit, the patents at issue are directed to pharmaceutical formulations – or “batches” – of the drug bivalirudin that are produced through a process that consistently minimizes impurities in batches of the drug that are compounded with a base. As part of receiving FDA approval for their product, Medicines was required to limit the level of a certain impurity to less than 1.5 percent. This requirement ultimately led to inventors for Medicines developing technology reflected in the patents at issue that minimized localized “hot spots” in batches that were produced by Medicines using a previous manufacturing process that resulted in levels of the impurity above 1.5 percent.

Ultimately, the new production method developed by Medicines led to levels of the impurity that did not go beyond 0.6 percent, and so a limitation was included in the claims to both of Medicines’ patents that recited “wherein the batches have a maximum impurity level of Asp9-bivalirudin that does not exceed about 0.6%”. The claims for one of the patents also required “efficient mixing” to produce these batches, and the specification for both of the Medicines patents explicitly defined “batch”.

At the outset, the Federal Circuit noted that the batches limitation could not be literally construed to cover individual batches of bivalirudin having Asp9 levels that “do not exceed about 0.6%” because that would render the claims invalid over certain pre-critical-date sales made by Medicines itself using its old manufacturing process. Instead, the Federal Circuit indicated that “the batches limitation requires…use of a process that achieves batch consistency. This requirement follows from simply reading the batches limitation against the specification’s definition of the term ‘batches,’ as slightly revised by the district court with the agreement of the parties to clarify that the ‘batches’ must be made by a particular compounding process.”

According to the Federal Circuit, “[t]hat definition limits the ‘batches’ claimed by the patents in suit to either ‘all batches prepared by a same compounding process,’ or ‘a single batch…wherein the levels of [Asp9-bivalirudin] represent levels for all potential batches made by said process…The batches limitation therefore requires a process that achieves consistency between batches produced from the ‘same compounding process’ – i.e., batch consistency [emphasis original].”

At oral argument, Medicines even admitted that what distinguishes its patent from its own pre-critical-date sales was batch consistency that was achieved by following the process of the patents at issue, even though it took the position on appeal that the batches limitation was not necessarily limited to that compounding process and was instead satisfied whenever an accused infringer consistently produces batches having Asp9 levels below 0.6 percent. Medicines took this position since the claims do not require the use of a particular process that achieves batch consistency.

However, the Federal Circuit stated that Medicines’ interpretation, among other things, fails to consider the specification and prosecution history of the patents in suit, both of which demonstrate that the invention disclosed by the patents is a compounding process that achieves batch consistency. “The specification, for example, states that ‘development of a compounding process for formulating bivalirudin that consistently generates formulations having low levels of impurities is desirable’…and that ‘the compounding process…of the invention described herein may consistently generate pharmaceutical batches…having the same characteristics [emphasis original].”

Furthermore, “[d]uring prosecution of the [patents at issue], Medicines further represented that ‘[i]n the present invention, various embodiments relate to a less subjective and more consistent process for the mixing of the pH-adjusting solution with the bivalirudin solution.’…Medicines also took pains to distinguish its pre-critical date sales of [its old product] in observing that ‘[p]harmaceutical batches…as described [by the patents in suit], and as prepared by the new process of the present invention…have not been on sale/marketed/or offered for sale for more than one (1) year as of the [patents’] filing date [emphasis original].’”

The Federal Circuit went on to note that Medicines even admitted to the district court that “[w]hen viewed in the context of the specification, it is readily apparent that the [definition of ‘pharmaceutical batches’] refers to the compounding processes described in the patents-in-suit.”

“Thus, we reject Medicines’ interpretation and conclude that the batches limitation requires the use of a compounding process that achieves batch consistency. In doing so, we note that our decision does not impermissibly add a process limitation to a product claim that does not require a process because the specification’s definition of ‘batches’ by itself injects a compounding process as a limitation in the asserted claims.”

The Federal Circuit went on to hold that “efficient mixing” is required even though not recited in all the claims since no other way was disclosed in the specifications of the patents at issue and those specifications explicitly stated “[t]his compounding process includes all of the embodiments as described [emphasis original].” The Federal Circuit then stated that the “specification therefore teaches efficient mixing as a necessary and sufficient condition for achieving batch consistency” and that the prosecution history confirms this since Medicines highlighted that what distinguishes the patents at issue from its old process was efficient mixing not performed using the old process. Hence, inefficient mixing was disclaimed.

The Federal Circuit then sought out to determine what was meant by “efficient mixing”. Medicines indicated it should be construed to mean “mixing [that] is characterized by minimizing levels of Asp9-bivalirudin in the compounding solution,” i.e., below 0.6 percent. However, the Federal Circuit disagreed since, even though that statement was taken verbatim from the specification, “it does not purport to be definitional because it does not accord with the linguistic formula used by the patentee to signal the designation of other defined terms – including ‘batches.’” Thus, despite a statement that clearly characterized a term, “because [the statement] departs from this format, the statement Medicines relies on lacks the clear expression of intent necessary for a patentee to act as its own lexicographer.” In other words, the patentee’s unequivocal statement lacked “clear expression of intent” because it did not follow the same “linguistic formula” the patentee used in other parts of its own specification. Whether this is now a new test for how to define claim terms in the specification will be left to future cases to develop.

The Federal Circuit also noted that Medicines’ preferred statement essentially reflects functional language that covers any way of mixing that achieves a compounding solution having an Asp9 level of less than 0.6 percent. “The patentee’s construction of ‘efficient mixing’ thus attempts to claim all solutions to the identified ‘impurities’ problem, without describing the entire range of solutions to that problem. Medicines’ construction is therefore not permissible.”

The Federal Circuit ultimately held that Mylan’s ANDA did not infringe the asserted claims.

This case provides some key takeaways for patent practitioners, some more obvious than others. First, as has been known for some time, referring to the “invention” in a patent’s specification can hurt, as can indicating that a particular process “includes all” of the embodiments the specification describes. This is why patents for inventions in the U.S. now curiously, if understandably, usually avoid using the word “invention”. Also, setting forth definitions in a specification can have unintended consequences not just for the term being defined but also for terms that are not explicitly defined even if unequivocally characterized in some other way. Prosecution history also matters too, particularly where an applicant distinguishes its invention during prosecution by explicitly characterizing “the invention” in terms divorced from the language of the claims themselves.

The Author

John M. Rogitz
is a registered patent attorney with his own practice in San Diego, CA. His background includes preparation and prosecution of a large number of patent applications for high-tech Fortune 500 companies in a wide range of technologies. John has also been active on behalf of his clients in the acquisition of patent portfolios. He writes frequently for various publications on developments in patent law and also lectures on intellectual property for DeVry University. Previously, John was engaged in civil litigation at the Watkins Firm, a San Diego-based law firm. Prior to that, he worked as a web developer for Loyola Marymount University. John received his J.D. in 2009 from California Western School of Law.

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